Sunday, August 3, 2008

Unpacking Goals

After working through Chapter 6 and looking at the content standards again, I've taken another look at my big ideas, the stated or implied real-world performances that go with the standards, and the essential questions that fit best with the standards.

  1. Interconnections between species
  2. The flow and cycling of resources (energy and nutrients) in ecosystems
  3. Ecosystem responses to disturbance

Students should be able to...
  • ANALYZE changes in an ecosystem.
  • REPRESENT energy flow through an ecosystem, as in an energy pyramid.
  • DISTINGUISH accommodation within individuals from genetic adaptation in a population. (I'm saving this for Unit 3 when we get into evolution.)
  • DETERMINE the fluctuations in population size caused by birth, immigration, emigration, and death.


Students should understand that...
  • Ecosystems include a variety of different roles that can interact in complex ways. (Big Idea #1)
  • Both negative interactions (competition, predation) and positive interactions (cooperation, mutualism) are important in shaping the structure of ecological communities. (#1)
  • Different species use different survival strategies, which can be successful in very different ways (e.g., r-selection vs. K-selection; Type I, II and III survival curves).
  • Species' populations can be regulated from the "bottom up" (by resource limitation) or from the "top down" (by predation and disease). (#1, #2)
  • Nutrients cycle within the biosphere: carbon, nitrogen, oxygen, and water are reused again and again, with little "new" input or loss (though human CO2 production is a major exception!). (#2)
  • Ecosystems are open-ended with respect to energy: producers obtain it from one source (almost always the sun) and pass it up the food chain, losing some energy to heat at every step. (#2)
  • Some ecosystems depend on "keystone species", and that threatening these species threatens the entire structure of the community. (#3)
  • Outside disturbance can upset the balance of an ecosystem, and that the degree of upset depends on both the magnitude of the disturbance and the robustness of the ecosystem. (#3)
  • How are different species dependent on each other?
  • Why is preserving biodiversity important?
  • What makes an ecosystem stable or vulnerable?
  • How do resource needs constrain the structure of ecological communities?
  • How can we protect ecosystems from damage, and when should we do so?
  • Have students plot the flow of resources and/or interaction webs in sample ecosystems.
  • Write the "biography of a nitrogen atom" (or a carbon atom, etc.) as it journeys through its nutrient cycle.
  • Examine population data to determine if a species is at its carrying capacity in a particular ecosystem.
  • Identify populations that are under "bottom-up" or "top-down" regulation.
  • Study real-world systems where dramatic shifts have occurred in community structure, and identify likely causes for the change.
  • Research an exotic species that has been introduced to California (chosen from a list) and present a report explaining whether it has become invasive, how they can tell, and what is being done to combat it (if anything).
At this point I think my Stage 1 picture looks pretty clear. Assuming that my coaches agree, I'll be ready to jump into Stage 2: designing the assessments that will allow my students to demonstrate their understanding of the material.

1 comment:

Page Tompkins said...

Go... I look forward to seeing how you want to bring this to life! Also, knowing that many of your students have significant learning challenges (primary language may not be English, several of your students likely read well below grade level) I look forward to hearing your ideas about how you can help all different types and levels of students access these very high level, compelling, and important ideas.